W/Ni比对NiO-WO3/γ-Al2O3催化剂异丁烷氧化脱氢性能的影响

摘要采用分步浸渍法制备了NiO-WO₃/γ-Al₂O₃系列催化剂,运用X射线衍射(XRD),激光拉曼光谱(Raman),程序升温还原(TPR),氨气程序升温脱附(NH₃-TPD),紫外-可见漫反射光谱(UV-vis DRS)等方法考察了n(W)/n(Ni+W)比例对NiO-WO₃/γ-Al₂O₃催化剂的表面结构、氧化还原性能、酸碱性以及异丁烷氧化脱氢制异丁烯性能的影响。研究结果表明,n(W)/n(Ni)比例对NiO-WO₃/γ-Al₂O₃系列催化剂的表面活性物种种类有较大影响,当W含量较高时,其表面主要形成WO₃晶粒和Ni-Al尖晶石,而当W含量较少时,表面主要形成聚钨酸盐、NiWO₄和Ni-Al尖晶石物种;适量的W存在有利于提高NiO-WO₃/γ-Al₂O₃催化剂的氧化还原性能和可还原晶格氧数量,并且增加W的比例能够提高催化剂表面强酸中心的数量。n(W)/n(Ni)存在最适宜比例,当n(W)/n(Ni+W)=0.2,NiO-WO₃/γ-Al₂O₃催化剂具有最佳的异丁烷氧化脱氢性能,这与催化剂表面的活性物种具有较好的脱氢性能、可还原晶格氧物种的增多以及表面强酸中心数量的提高有关。

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关键词： n(W)/n(Ni); NiO-WO₃/γ-Al₂O₃; 选择性氧化脱氢; 异丁烷; 异丁烯

Abstract： NiO-WO₃/γ-Al₂O₃catalysts were prepared by stepwise impregnation method. The catalysts were characterized by X-ray diffraction, FT-Raman spectroscopy, temperature programmed reduction, NH₃-temperature programmed desorption, UV-diffuse reflectance spectrum. The effects of W/Ni ratio on surface structure, distribution of active species and catalytic performance for selective oxidation of isobutane were investigated. The results show that n(W)/n(Ni) has a significant impact to surface active species of catalysts. WO₃ crystal and Ni-Al spinel are mainly observed when the W content increases. However, in Ni-rich catalysts, polytungstate, NiWO₄ and Ni-Al spinel species are mainly observed on the surface of catalysts. Addition of W at a proper amount obviously improves the catalytic performance of catalyst for selective oxidation of isobutene and the number of strong acid sites on the catalyst surface. The catalysts have the best performance for selective oxidation of isobutene when n(W)/n(Ni+W)=0.2, which is especially related to dehydrogenation capability of active species, lattice oxygen activity and surface acidity of the catalyst.

Keywords： n(W)/n(Ni); NiO-WO₃/γ-Al₂O₃ catalyst; selective oxidative dehydrogenation; isobutane; isobutene

Received 2013-03-25;

Corresponding Authors: 王希涛,E-mail:wangxt@tju.edu.cn。 Email: wangxt@tju.edu.cn

About author: 陈川(1987-),男,主要研究方向为工业异丁烷氧化催化脱氢法。

引用本文:

陈川, 王希涛.W/Ni比对NiO-WO₃/γ-Al₂O₃催化剂异丁烷氧化脱氢性能的影响[J]. 化学工业与工程, 2015,32(1): 26-30

Chen Chuan, Wang Xitao.Effects of W/Ni on the Catalytic Performance of NiO-WO₃/γ-Al₂O₃ Catalyst for Oxidative Dehydrogenation of Isobutane[J]. Chemcial Industry and Engineering, 2015,32(1): 26-30